Hosts or Prey
Whiteflies, such as ash whitefly
Identification
All stages of C. arcuatus occur openly on whitefly-infested leaves and shoots. The adult lady beetle (ladybug or ladybird beetle) is about 1/16 inch (1.5 mm) long. It is oval to round when viewed from above and dome shaped (convex) when viewed from the side. The body is covered with short hairs. The thorax is brown and whitish and the wing covers are mostly dark brown to yellowish brown. At the center of the wing covers is a relatively large, dark brown blotch. The sides and rear of the brown blotch are bordered by white or yellow, curved spots that are faint in some individuals and obvious in other individuals.
Eggs are pale, oval shaped, and about 1/100 inch (0.2 mm) long. Larvae are elongate and pale yellow to whitish. They are covered with pale, short hairs and have distinct segments. Mature larvae and pupae are about 1/16 inch (1.5 mm) long. Pupae are oblong and mostly whitish with dark markings. As they age, they develop distinct appendages folded against the body.
Life Cycle
Lady beetles develop through 4 life stages: egg, larva, pupa, and adult. An adult female on average lives about 12 weeks during which she lays about 200 eggs. Adults and larvae feed on all stages of whiteflies but prefer whitefly eggs and nymphs. A single adult female is capable of feeding on up to 10,000 whitefly eggs during her lifetime.
The hatching larvae develop through four increasingly larger instars as they feed. Mature larvae pupate openly on host plants.
The lady beetle has about four generations per year. It spends the winter as diapausing (inactive) adults in hidden or protected places.
Habitat
Ash whitefly was inadvertently introduced into Southern California in about 1986 and it spread throughout most of the state. On preferred hosts (e.g., apple, ash, pear, and pomegranate) the whitefly infested 100 percent of the leaves. This caused extensive defoliation and sticky honeydew and blackish sooty mold that fouled plants and surfaces beneath them. In some cases, the whitefly's repeated defoliation of hosts caused the plants’ premature death.
The pest's annoyance and damage prompted entomologists from the California Department of Food and Agriculture and University of California to search for effective natural enemies in the Near East and Mediterranean Region where the whitefly is believed to be native. Encarsia inaron (a parasitic wasp) and C. arcuatus were collected and studied under quarantine, which revealed they do not attack beneficial species.
In 1989 C. arcuatus from Israel was imported into California. It was mass reared and along with the parasitic wasp released at various locations with ash whitefly infestations. These natural enemies spread everywhere the whitefly occurs and especially E. inaron reduced the abundance of ash whitefly to innocuous levels. The economic benefit of this classical biological control program that improves the aesthetic quality of plants and avoids the costs of ongoing management is over $200 million per year in perpetuity.
Species
At least 17 Clitostethus species occur in the world and all are specialized predators of whiteflies. Clitostethus arcuatus is the only member of its genus reported in California. It feeds on numerous species of whiteflies including ash whitefly, citrus whitefly, greenhouse whitefly, and woolly whitefly.
More Information
- Ash Whitefly, In Biological Control in the Western United States, UC Agriculture and Natural Resources
- Ash Whitefly (Homoptera: Aleyrodidae) Overwintering and Biological Control by Encarsia inaron (Hymenoptera: Aphelinidae) in Northern California, UC IPM Program, Environmental Entomology
- Biological Control of Ash Whitefly: A Success in Progress, California Agriculture
- Development, Survival, Longevity, and Fecundity of Clitostethus arcuatus (Coleoptera: Coccinellidae) on Siphoninus phillyreae (Homoptera: Aleyrodidae) in the Laboratory, UC Riverside, Environmental Entomology
- Establishment of the Ash Whitefly Parasitoid Encarsia inaron (Walker) and its Economic Benefit to Ornamental Street Trees in California, Biological Control
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Coccinellidae